Tonight ITV will air much-anticipated drama A Confession which details the disappearance of 22-year-old Swindon native Sian O'Callaghan in March 2011 and the events that led to the jailing of her killer Christopher Halliwell.

Evil Halliwell also admitted to killing Becky Godden, who had disappeared from the Wiltshire town a decade earlier.

But police have not ruled out that more women may have fallen victim to Halliwell.

Following the discovery, extensive searches of the Hill Drop Lane area were carried, including the use of a specialist dive team from Avon and Somerset and cadaver dogs from South Wales.

Thousands of litres of water from the 8ft deep pond were reported to have bee drained and sieved to see what might be hidden at the bottom under several inches of silt.

Wiltshire Police said they had located up to 60 pieces of women's clothing buried under two inches of soil in thick woodland about 100 yards from the pond. They also found a chunky knit cardigan close to the water.

Sian O'Callaghan disappeared following a night out in March 2011 (Image: PA)

Detective Chief Inspector Sean Memory said he was confident the clothing found in the woodland did not belong to Miss O'Callaghan.

He said he did not know how long the clothing had been hidden but had been there for "some time".

"Someone has made some effort to hide it. There are in excess of 60 items of material, such as a sleeve, a zip or a hood, so it is difficult to say exactly how many items of clothing there are," Mr Memory said at the time.

"There may be a really innocent explanation and someone may have fly-tipped it. Equally it is really unusual to find women's clothing buried.

"It may genuinely have no significance at all but I am open minded as to why someone would bury clothing.

"But to me it does seem a very strange location to be burying clothes, given what else we have found here.

"I am satisfied the clothing does not relate to Sian O'Callaghan but I don't know what Becky Godden was wearing when she disappeared or exactly when she disappeared."

The detective who helped Halliwell behind bars, Steve Fulcher, has also shared his belief that there could be dozens more victims.

"Are you seriously telling me that on two occasions he brutally murdered two women – and then there’s nothing before or since?” he asked.

Speaking in his 2017 book Catching A Serial Killer, Steve spoke of Halliwell's confession of the location of Sian O'Callaghan's body.

"At the bottom of a pond that was 8ft deep they found Sian O’Callaghan’s distinctive boot.

“Yet that wasn’t all. Halliwell had been busy. Buried around the pond were more items of women’s ­clothing. I wondered, did they belong to the six other victims I suspected Halliwell of killing? But I had my maths wrong.

“Around the pond were not six other items of women’s clothing. There were 60. Halliwell might have been far more prolific than even I had feared,” revealed Fulcher.

Martin Freeman stars as DS Steve Fulcher in six part ITV drama A Confession (Image: ITV)

Wiltshire Police had launched a high-profile enquiry when office worker Sian O'Callaghan, who lived with her boyfriend Kevin Reape, failed to return home after a night out in March 2011.

Under the leadership of Detective Superintendent Steve Fulcher, Halliwell quickly became a suspect in her abduction and murder.

But the investigation went off in unexpected directions, with the events to be told in new ITV drama A Confession.

*The Confession starts on ITV on Monday, September 2 at 9pm and has six episodes.